Computer Concepts and Terminology

Networking and Telecommunications

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You will often have the need to connect your computer to
other computers in order to share information. This is typically done
with a connection to a data network, or with a connection over a telephone
line.

Networking

A Local Area Network (LAN)
is used to connect computers spread over a relatively small area, such
as a university campus, or several offices in a building, or a home.
The computers on the network can share data, and they can also access
printers connected to the network. All of the computers and printers
on the network are called nodes of the network.

If your personal computer is connected to a network, it
is called a network workstation (note that
this is different form the usage of the term workstation as
a high-end microcomputer). If your PC is not connected to a network,
it is referred to as a standalone
computer.

In order to connect to a network, your computer
will need a network adapter. This circuitry and port could be built into
the motherboard or it could be on a network interface
card (NIC)
in one of the computer’s expansion slots. Your computer will also
need the necessary networking software installed. Ethernet is
the most common networking technology used.

If the computers connected to a network have equal status,
it is called a peer-to-peer network. A typical
home network might be done this way.

Larger LANs usually have one or more
computers that act as file
servers to provide data and software
to the other computers on the network. The other workstations are referred
as client computers, and this is a server/client network.
You may also find terminals connected
as nodes on a network (terminals have only a screen and a keyboard,
and no processing power; they connect over the network to a
computer that does the actual processing).

At UNM-A, we have a server (named Chicoma, after the tallest
mountain in the Jemez) on our campus LAN that validates your login name
and password when you use one of our PCs as a client workstation, and
provides files to network clients. Students can also use terminals in
building 3 (if we still have any in Room 306) to connect to Chicoma
to run software for some of our programming classes. In our Mac lab,
we use a peer-to-peer setup to allow the students to get files from the
teacher’s
Mac.

It is also possible to do wireless networking, and you
will see more of this in the future. A wireless LAN (WLAN) uses radio
waves to carry the network traffic. They are usually based on the IEEE
802.11 specification, also called Wi-Fi.

Telecommunications

Telecommunication refers
to transmitting data over a long distance. For personal computers, this
usually entails connecting to other computers over a telephone line or
other connection.

A telephone line carries an analog signal,
one that has a continuously varying waveform. This is different from
the discrete digital signals that represent
numbers in your computer. To communicate over a phone line, you computer
needs a modem (which
stands for modulator-demodulator).
The modem takes the digital information from your computer and modulates it
onto an analog wave in the range of sound frequencies that can be carried over
phone lines. The modem also takes analog signals from the phone line and demodulates
them to extract the digital information, which it passes to your computer. The
computer on the other end of the phone line is also equipped with a modem.

Computer modems typically communicate at 56K (56
kilobits per second), but if your phone connection is not good the modems
will shift to a slower speed at which a reliable exchange of data can
take place. A telecommunications connection via a phone modem is called
a dial-up connection.

Many modems can also function as fax machines. You can
“print” a document as a fax image to send to a distant fax machine.

Broadband

Many users found 56K telephone modem
connections too slow (especially with increased popularity of the Internet).
Broadband connections allow faster transfer
of information. The most popular kinds are DSL, cable, and satellite.

A DSL (Digital Subscriber Line) connection works over your
telephone line and requires a special DSL modem. Unlike a regular modem,
the DSL modem signal is carried at higher frequencies, beyond those of
sound. It has a wider bandwidth since it is not limited to the audio
band, and it has the advantage that you can use the telephone line simultaneously
for voice and DSL communications. DSL requires special equipment installed
at the phone company end, and you must not be located too far from the
phone company’s junction.

A cable connection (requiring a special cable modem) uses
your cable television line to transmit and receive data. Similarly, a
link to satellite TV broadcast satellites can be used to provide broadband
access to areas DSL or cable TV can't service.

Internet

One of the primary reasons for getting a
network or telecommunications connection for your computer is to access
the Internet. The Internet is a wide area network
(WAN) that spans the globe and uses the TCP/IP protocol to transmit information.
To access the Internet, you need a dial-up or broadband connection through
an Internet Service Provider (ISP), or access to a network that has a
gateway connection to the Internet.

Many information resources and services are available via
the Internet; the two most popular are electronic
mail (e-mail) and
the World Wide Web (the Web).
Both of these services use a client/server model: there are servers on
the Internet that handle e-mail traffic or offer web
pages. To access these, you need to run appropriate client software
on your computer. Popular e-mail clients include Thunderbird, Apple's
Mail program, and Outlook Express. World Wide Web client programs are
called web
browsers,
and popular examples are Internet Explorer, Chrome, Netscape, Opera,
Firefox, and Safari.

Electronic mail entails sending and receiving private messages
between users connected to the Internet. (This is different from public
posting of messages on electronic forums such as Usenet Newsgroups or
web forums.) Your messages are held for you on an e-mail server until
you access them using you e-mail client software.

The World Wide Web is free-format a collection
of data archives called web pages that include
text, graphics, animation, sound, and video. Web pages are linked together
using
hypertext links (hyperlinks);
simply clicking on a link displays another web page. All manner of
information is available on the Web from individuals, businesses, universities,
government bureaus, etc.